1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly to a liquid crystal display capable of improving the bending phenomenon of the liquid crystal panel.
2. Description of the Prior Art
A liquid crystal display is one of image display devices and has the advantages of lightness, flatness, and compactness, as well as low power consumption, compared with a CRT, which is a typical image display device. Unlike the CRT, the liquid crystal display cannot generate light by itself and needs a light source in addition to a liquid crystal panel. A fluorescent lamp is usually used as the light source of the liquid crystal display. Upper and lower polarization plates are attached to the upper and lower surfaces of the liquid crystal panel of the liquid crystal display, respectively, to interrupt or transmit light from a lamp.
FIG. 1 is a perspective view showing the structure of a polarization plate according to the prior art.
The polarization plate 16 according to the prior art has an adhesion layer 11, a first TAC (triacetylcelluose) film 12, a PVA (polyvinylalconol) film 13, a second TAC film 14, and a mold-release film 15 successively laminated. The PAV film 13 is elongated in a predetermined direction and is dyed with a pigment having two colors. The first and second TAC films 12 and 14 are attached to both surfaces of the PVA film 13, respectively. The adhesion layer 11 is made of a high-molecular material having adhesion force so that the polarization plate 16 is attached to an upper or lower substrate (not shown). The adhesion layer 11 has the same adhesion force to both upper and lower substrates. Reference numeral 10 refers to an adhesion protective film.
Such a conventional polarization plate 16 having an elongated film, such as the PVA film 13, however, bends in a predetermined direction as the PVA film 13 contracts in the direction of the elongation axis due to change in temperature or humidity. As the temperature resulting from the lamp rises very much, furthermore, the liquid crystal panel positioned on above the lamp is affected by the temperature and bends in a predetermined direction. The degree of bending of the liquid crystal panel becomes severer when the bending direction of the polarization plate 16 is identical to that of the liquid crystal panel.
FIG. 2 is a sectional view showing the bending direction of the liquid crystal panel and the upper and lower polarization plates according to the prior art. When the liquid crystal display according to the prior art is affected by temperature or humidity, the liquid crystal panel 30 bends in a predetermined direction and the upper and lower polarization plates 20 and 40 bends in directions opposite to each other. Consequently, any one of the upper and lower polarization plates 20 and 40 necessarily has the same bending direction as the liquid crystal panel 30. This adversely increases the degree of bending of the liquid crystal panel 30. It is difficult, in the end, to maintain uniform screen quality throughout the entire region of the liquid crystal panel 30. Although FIG. 2 shows a case wherein the bending direction of the upper polarization plate 20 is identical to that of the liquid crystal panel 30, the lower polarization plate 40 and the liquid crystal panel 30 may have the same bending direction (not shown) as mentioned above and the degree of bending of the liquid crystal panel 30 may become severer.